1. Field of the Invention
The present invention relates to a current programming apparatus, an active matrix display apparatus and a current programming method therefore, and is particularly advantageously employable in an active matrix display apparatus employing a current-driven display device.
2. Related Background Art
In an active matrix display apparatus employing a field light-emitting device, there is employed, in a drive circuit of each pixel, a current write-in circuit in which a drive current for the light emitting device is written and stored. In the present specification, an operation of writing and storing a drive current in each pixel of such matrix display apparatus is called a current programming, and a circuit for such purpose is called a current programming circuit.
In U.S. Pat. No. 6,686,699, FIG. 18 discloses a current programming circuit which retains a current to be supplied to a data line, as a gate-source voltage of a transistor. This article also describes that, at data writing in the current programming circuit, gradation displays of black and a low luminance level can be improved by flowing such current in a direction of canceling the writing current.
In a prior current write-in pixel circuit, the write-in operation of an image data current may not be executed in a stable manner in each pixel circuit. Such phenomenon will be explained later in more details. One of the causes of the phenomenon attributes to a parasitic capacitance of the data line. When the parasitic capacitance of the data line is large, a fluctuation of the threshold value of drive transistors becomes unnegligible for a small data current.
An object of the present invention is to provide a current programming apparatus, an active matrix display apparatus and a current programming method therefor, allowing to achieve a stable write-in operation of such image data current.